It has long been known that stationary and mobile part-structures in a living body can be observed with the aid of different types of ultrasonic scanners. The invention can also be applied to advantage in co-operation with an ultrasonic scanner provided with a scanning head, also referred to as an ultrasonic transducer, comprising a linear array of ultrasonic transmitters, in which each ultrasonic transmitter can include one or more ultrasonic crystals and in which each of the transmitters is activated in sequence, one after the other, to emit an ultrasonic beam pulse, and a common ultrasonic receiver. A two-dimensional image of a deep section in a living body is obtained with such a scanner and shown on a screen. The moving image presented on the screen provides certain information concerning the mobility of the illustrated part structures of the body, but are required to provide a clearer representation of the actual movements.
In an article "A Dual High-Resolution 2-Dimensional Ultrasond System for Measuring Target Movements" by G. Gennser, K. Lindstrom, P. Dahl, M. Benthin et al in RECENT ADVANCES IN ULTRASOUND DIAGONIS 3, PROCEEDINGS OF THE 4TH EUROPEAN CONGRESS IN ULTRASONICS IN MEDICINE, Dubrovnik May 1981, there is described how it is possible with the aid of an ultrasonic head having linearly placed multiple ultrasonic transmitters to measure continually the momentary inner dimensions between two defining surfaces of a mobile, e.g. pulsating structure, in a living body, such as the aorta of human foetus. By taking these measurements at close time intervals, i.e. between each indication of a horizontal line, there is obtained a dimensional change at many points in time during the duration of one pulsation, and a pulsation diagram of pulsewave diagram can be drawn for a section through a pulsatile vessel or vein. In the penultimate paragraph on page 73 of the aforesaid article it is said that there are two markers although it should be noted here that the two markers are placed at two locations on the same horizontal line as that used as measuring lines, so that two markers here correspond to one of the elongated markers described hereinafter in the description.
The method described in this article has been found extremely valuable for providing visual pictures of movements, particularly of pulsating part structures in a living body, such as a blood vessel. The article, however, is only informative in respect of movement in one direction, i.e. the change in diameter as a function of time right through a part structure. This information gives only a limited picture of the state of the mobile part structure being measured, since the part structure, particularly when it is a blood vessel, partly leads a pulse wave in a direction transversely to that in which the change in diameter is indicated, and partly may undergo changes in this transverse direction which renders the pulsation diagram obtained in accordance with the known method highly dependent on which part structure the measurements are carried out. This circumstance is particularly applicable to arteries, especially in respect of older people where various types of constriction can be found relatively frequently. Consequently, there is a need of indicating changes in more than one dimension of movable structures.